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Topic: 69 Z/28 metal vacuum line correct? (Read 9421 times)

I don't know if this was a 302 only issue so it could apply to the 350 as well. I am trying to figure out if vacuum line from the distributor which had a metal line and metal clip that bolts to the intake, was used throughout the year, or if there was a mid year change to all rubber from distributor to carb. I would appreciate if guys that have the original metal lines and the clip could respond with build dates, or motor dates. I also would appreciate if any guys with original motors with an all rubber line, and no clip on the intake could post the build date of their cars. I don't have a good picture of this, other than what John Z did rerouting his. So if you have a original picture please post it. thank you for the help.

On the L48 with Q-jet it was a combination of metal tube bent to go around the carb base and white striped hose on either end connecting to carb port and vacuum advance port. I think it was called "pipe spark" 3870334 in the AIM. http://www.classicindustries.com/camaro/parts/k0054a.html

Here's the original arrangement on a Z/28 with the steel tube and rubber hose; the L48 was set up exactly the same as the L35 (AIM section L35, sheet A6, View "B"), with the steel line, clip, and rubber hose.

Ok, great I appreciate the info on both motors, and the picture. Now is anyone aware if this process was used throughout the 69 production year? or was there a change mid year to a full rubber hose? Thanks for the help

Not trying to Highjack this thread but Would someone post a picture of where the "69 4 speed L48 Vacuum Advance Line hooks up to the carburetor? I've saw it in pictures in 2 different places and the AIM looks too fuzzy on that page.

Not trying to Highjack this thread but Would someone post a picture of where the "69 4 speed L48 Vacuum Advance Line hooks up to the carburetor? I've saw it in pictures in 2 different places and the AIM looks too fuzzy on that page.

I just pulled my carb off for cleaning and rebuild, and some intake detailing but here is a pic from the web of an L48 and 7029203 DY carb 4 speed Muncie.

The set-up is a reversed "J" hooking around the Q-Jet base at the front pass side then connecting at the drivers side front ported vacuum source (no vacuum at idle).

Just a note in research I have found that some Corvette and Chevelle guys use the pass side vacuum port (in the photo capped with a blue plug) which is for automatic transmission vehicles to drive the heat stove flap in the air cleaner snorkel, to drive the dizzy vacuum advance. But this requires different weights in the dizzy and setting the tuning to match. So if yours is already hooked up there you can go back to factory setup but you will have to set your timing to base line first.

The factory front drivers side port only gets vacuum as the primaries and secondaries are used not the idle.

Its a non illustrated item on RPO L48 but the notes say same as L35 where it is illustrated on page 280, view B [/quote]

Thanks for the picture and information. With what you had posted previously and what JohnZ posted about the L35 I finally got it figured out. The note in my AIM is illegible. This picture is an auto. Where can I find full manifold vacuum on a manual intake for my vacuum advance? The only port on my carb is the choke pull off or the brake booster.

Thanks for the picture and information. With what you had posted previously and what JohnZ posted about the L35 I finally got it figured out. The note in my AIM is illegible. This picture is an auto. Where can I find full manifold vacuum on a manual intake for my vacuum advance? The only port on my carb is the choke pull off or the brake booster.

The vacuum fitting on top of the intake, behind the carburetor, is a manifold vacuum source.

Thanks for the picture and information. With what you had posted previously and what JohnZ posted about the L35 I finally got it figured out. The note in my AIM is illegible. This picture is an auto. Where can I find full manifold vacuum on a manual intake for my vacuum advance? The only port on my carb is the choke pull off or the brake booster.

The vacuum fitting on top of the intake, behind the carburetor, is a manifold vacuum source.

I'll have to change the fitting that the brake booster uses so it has another outlet. Correct?

Thanks for the picture and information. ... This picture is an auto. ...

No the picture I posted for the L48 is a Manual vehicle. As stated brake and RS headlights take vacuum from the intake manifold nipple behind the carb base. Use a T if you have both, single L id only Power Brakes. Vacuum advance is the port pictured on the front drivers side.

The large port at the base of the carb base is for your PCV valve hose.

I don't have an picture of an automatic vehicle, but it would have a kick-down mounted to the throttle linkage and would be using the pass side vacuum port with the blue cap to drive the heat stove in the snorkel.

Thanks for the picture and information. ... This picture is an auto. ...

No the picture I posted for the L48 is a Manual vehicle.

I don't have an picture of an automatic vehicle, but it would have a kick-down mounted to the throttle linkage and would be using the pass side vacuum port with the blue cap to drive the heat stove in the snorkel.

I see the accelerator rod. What's that black linkage that's hooked to the throttle? It looks like a kick down cable to me. That's why I thought it was an auto.